Tractor mechanic help

[Hawkins]

We have a Kubota diesel tractor, probably about a 35 to 40 hp. A few months ago it was running bad, it had trash in the fuel tank, stopping up the fuel lines. We changed the fuel filter and blew out the fuel line and cleaned the tank. It ran good for a while. Now it is runnng bad again, but a little different than last time. It will idle all day long, but when you throttle it up it will go to about 2500 rpms for a few seconds then loose power till it almost dies and it will sputter back to an idle. It will not run with the little bleed valve closed like it should be. (round knob that you open to bleed off air after you change the fuel filter) It will barely run at all under load, pto going and it in gear.

The air filter is good, we even tried it with it off.
Fuel filter is clean. The fuel bowl stays full of fuel, so the tank doesn't seem plugged up like last time.
Ran it with the fuel cap off to make sure it wasn't creating a vacuum or a vent was clogged up.

This weekend I was gonna loosen off each injector line and crank it and make sure they are getting fuel.

I am not a mechanic at all, am I missing anything?

thanks

[bwssr]

could have crap IN the injectors, or in the pump

[Tmag]

Sounds like it is not getting fuel to me. I would blow the lines in reverse from the cylnder to the pump, pump to filter, filter to tank, and double check the tank. Could have some trash in the pump itself. Try it without the filters and see if they are restricting flow, I have seen this problem before. Filters could be trashed inside where you can't see it.

[Hawkins]

I'll try that Tmag, what would be the reason it won't run with the bleed valve closed? Last time it had trash in the tank it would run with it closed like it is supposed to, just wouldn't run long.

[rubydog]

It is a fuel issue. Do what is stated above and get her cleaned out...

[Texas Tracker]

Sounds like your injectors need to be cleaned or replaced. Pull them and have them tested.

[Tmag]

I'll try that Tmag, what would be the reason it won't run with the bleed valve closed? Last time it had trash in the tank it would run with it closed like it is supposed to, just wouldn't run long.

Not sure, just throwing out what I have dealt with in the past. Never did the bleed valve thing. Have you removed the fuel valve from the tank? There is a screen filter there that could be restricting flow too.

The injectors would be my next step after checking everything else.

[papapross]

Sounds like it is not getting fuel to me. I would blow the lines in reverse from the cylnder to the pump, pump to filter, filter to tank, and double check the tank. Could have some trash in the pump itself. Try it without the filters and see if they are restricting flow, I have seen this problem before. Filters could be trashed inside where you can't see it.

I would do this to make sure fuel will flow correctly and then I would add some Marvel mystery oil to the fuel. I have seen some bad running engines run smooth after doing this and still running ok.